The 3rd Generation Partner Project (3GPP) had some discussion on emergency call, for example, IMS and SRVCC. Emergency is discussed in some 3gpp standards including, for example, TS 23.167 (“IP Multimedia Subsystem (IMS) emergency sessions”); TS 23.509 (“TISPAN; NGN Architecture to support emergency communication from citizen to authority”); TR 23.870 (“Single Radio Voice Call Continuity (SR-VCC) support for IMS Emergency Calls”), etc.
Conventionally, the emergency handling mentioned above mainly focuses on a UE level. Generally, UE-level emergency handling provides communication service to individual in emergency. While under emergency situation, the network traffic model is changing dramatically, as well as the urgency requirement on basic voice service, so how to optimize network resource to ensure basic voice service and avoid network overload become very important.